Many engines having two oppositely working pistons within a single cylinder (opposed piston) have been invented and built. Many have proven to be inherently balanced and have high fuel and thermal efficiency providing the efficacy of the opposed piston concept. Except for one, those engines that have succeeded, as far as I know, have had multiple crankshafts. To my knowledge the only successful engine in use today which utilizes a single crankshaft, does so by using rocker levers to couple the pistons to the crankshaft. This engine however, works in multiples of single cylinders requiring two rocker levers and four connecting rods per cylinder thereby adding weight and increasing the number of working parts. The double number of connector rods all remain compressive members and therefore permit no reduction in weight.
In contradistinction the engine of the present invention uses two non-pivoting bridge members and three tensile connecting rods for each pair of cylinders resulting in better than 50% reduction in pivotally oscillating, drive-associated parts per working cylinder and permits lighter weight connecting rods which are all driven in tension rather than in compression.
In addition to the above reference the following list of patents is the best prior art on the hereinbefore described type of multiple cylinder opposed piston engines known to me as of the filing of this application.
British Pat. No. 10,981 of 1908 PA1 British Pat. No. 19,677 of 1912 PA1 British Pat. No. 483,063 of 1936 PA1 U.S. Pat. No. 2,203,648--June 4, 1940 PA1 U.S. Pat. No. 1,629,878--May 27, 1927 PA1 U.S. Pat. No. 1,679,976--Aug. 7, 1928 PA1 U.S. Pat. No. 2,129,172--Sept. 6, 1938 PA1 U.S. Pat. No. 2,159,197--May 23, 1939 PA1 Some Unusual Engines, by L. J. K. Setright, Mechanical Engineering Publications Ltd., London, England, 1975, pages 85-88.
The best prior art of the single cylinder opposed piston prior engines are:
Publication:
My U.K. patent application GB No. 2017819A based on now abandoned Ser. No. 890,980 was published Oct. 10, 1979 and the patent issued Aug. 18, 1982.
Primarily, in my opinion, because they are overly complicated with levers, long reaching and vibration prone connecting rods, valves and valve actuators, or eccentric, twisting or rocking loads being applied to the crankshaft and/or to the engine structure, few if any of the above engines have passed the test of time.